Canto-pop singer Kelvin Kwan Chor-yiu apologised last night as he returned to Hong Kong after being detained in Japan for cannabis possession.

'I am sorry. I committed such a big mistake. I'll hold a press conference to explain it later,' Kwan said as he walked into the airport's arrivals hall, where he was besieged by nearly 100 journalists.

He declined to elaborate and tried in vain to penetrate the media pack for 10 minutes. Eventually, he stepped back into the restricted area with the help of a few police officers and left through another exit.

Kwan's flight from Tokyo arrived at 8.26pm but he entered the arrivals hall at around 10pm.

Kwan, 25, and singer Jill Vidal, 26, who are believed to be linked romantically, were arrested in the Dogenzaka shopping area in Tokyo's trendy Shibuya district on February 24.

Police were called to the scene by a shopkeeper who suspected the singers were stealing merchandise. Police found a rolled-up cigarette containing about 0.2 grams of cannabis in their luggage.

Both stars were detained in Japan but it was unclear whether any charges were filed against them.

Vidal did not appear at the airport with Kwan last night and he ignored questions about her.

Kwan was accompanied by police officers to his home in Tin Hau and was assisting an investigation by the Narcotics Bureau.

His father said at the airport last night that he hoped his son would learn from the mistake.

Kwan reportedly told Japanese police that he brought the drug from Hong Kong. Vidal denied any criminal behaviour, saying she had no idea the packet contained cannabis.